Problem: It is given that x​ varies directly as y and inversely as the square of z​, and that x=10 when y=4 and z=14. Then, when y=16 and z=7,x​ equals:
Answer Choices:
A. 180
B. 160
C. 154
D. 140
E. 120
Solution:
x=Z2Ky​10=142K(4)​∴ K=410⋅142​
∴x=72410.142​⋅16​=160